1. Field of the Invention
This invention relates generally to catheter fittings which are adapted to inject substances into humans and animals and/or to withdraw specimens therefrom, and more particularly to a catheter fitting having a protective end seal at the connection end for preventing fluid leakage during installation, connection, and use.
2. Brief Description of the Prior Art
Catheters are hollow tubular devices which are inserted into a cavity, duct, vessel, or vein to permit injection or withdrawal of fluids from a patient. Existing catheters are commonly provided in a sterile package assembled with a catheter needle inside the catheter and an end plug in the back end of the needle. A tubular manually removable protective sheath covers the forward end of the needle and catheter.
The catheter has an elongate small diameter flexible tubular front portion and an enlarged diameter rear portion or base portion at the back end in which has an interior bore in communication with the interior of the tubular portion. The exterior of the catheter base may be provided with a small radial flange or other conventional configuration. The interior bore of the catheter base portion may be smooth or may have conventional Leur lock threads for connecting the catheter to various intravenous tubular members when the needle is removed.
The catheter needle has a hollow tubular needle body with a beveled front end to facilitate hypodermic and intravenous insertion and has a tubular base portion at the back end in communication with the interior bore of the needle. The exterior of the needle base portion may be provided with a bead or otherwise configured to receive a protective sheath. The rear portion of the needle base has an interior bore which usually is provided with plug slidably received therein. The plug has a reduced diameter forward portion which may be tapered to frictionally engage the bore at the rear end of the needle and an enlarged diameter rear portion which has flat surfaces on the exterior to facilitate griping with the fingertips to remove the plug. The plug is also usually provided with a small interior bore.
In the assembled and packaged condition, the needle is installed in the catheter with its base member engaged in the interior bore of the catheter base and the plug frictionally engaged in the bore at the rear end of the needle. The protective sheath is received over the catheter and engaged on the larger diameter of the needle base. The interior diameter of the catheter tubular front portion closely surrounds the forward portion of the needle but allows axial sliding movement of needle therethrough. The length of the catheter tubular portion is slightly shorter than the length of the needle so that the beveled front end of the needle is exposed to facilitate intravenous insertion of both the needle and flexible tubular portion of the catheter. A removable tubular protective sheath is received on the needle base and the forward portion of the needle and catheter and has an enclosed front end to prevent accidental pricking by the needle.
In using the conventional catheter, the catheter assembly is removed from its package and the protective sheath is removed. The beveled end of the needle having the tubular portion of the catheter surrounding its length is inserted into the vein. When the vein is penetrated, blood will flow into the needle and will be visible in the base portion of the needle and will also be drawn into the small bore of the plug due to capillary action. This detection of the fluid will signal that a suitable penetration has been made.
While the catheter is held stationary, the plug is removed from the needle or the needle is withdrawn from the catheter. The person installing the catheter must then connect another tubular fitting to the open rear end of the needle or the catheter to complete the fluid injection or withdrawal procedure. However, between the time the plug is removed from the needle or the needle is withdrawn from the catheter and the open end is connected, the body fluids will continue to flow unobstructed through the catheter and/or needle. This unnecessary flow presents many problems.
One problem arises because the person installing the catheter must hold the catheter stationary with one hand and remove the plug from the needle or withdraw the needle from the catheter with the other hand and then effect the connection. Thus, there is exposure to the free flowing body fluids during the interval between the time the plug is removed from the needle or the needle is withdrawn from the catheter and the open end is connected.
Another problem is that the person installing the catheter must very quickly remove the plug from the needle or withdraw the needle from the catheter with only one hand available. Often, the removed plug or needle will be haphazardly placed on the nearest convenient surface while connecting another tubular fitting to the open rear end of the needle or the catheter. As a result, the cap or needle may be lost in the bed covers or on the floor so there is exposure to both contaminated body fluids and to an exposed needle which could result in accidental pricking by the needle. Thus, the person installing the catheter, the patient, others in the room, and even hospital personnel cleaning the room or the bed linens are exposed.
The unnecessary leakage of body fluids is of critical concern to health practitioners from the standpoint of both handling the catheter and the needle during installation and removal and the disposal of used catheters and needles. Accidental exposure to some contaminated body fluids can have very serious and even fatal health consequences. For example, the body fluid may be contaminated with diseases such as hepatitis or A.I.D.S.
It would therefore be desirable to provide a catheter which would automatically seal at the open end to prevent fluid leakage when a needle or fitting is removed and would still allow connection of the catheter to other devices with the seal in place. Such a device would allow sufficient time for the person installing the catheter to properly shield and dispose of the needle with a minimum of handling and in a reliable and efficient manner to provide protection from accidental exposure to contaminated body fluids and puncture from lost needles.
There are many devices for shielding a hypodermic needle against accidental puncture and for covering the needle for disposal. However, there is no known commercially available catheter having a protective seal which eliminates the problems discussed above.
The present invention is distinguished over the prior art in general, and these patents in particular by an intravenous catheter which has an elongate small diameter flexible tubular front portion and a rear base portion which has an interior bore in communication with the interior of the tubular portion for connection to a needle or other fluid ejection or withdrawal members. A thin flexible membrane seal formed of resilient stretchable material is secured over the opening at the rear of the catheter base. The elasticity of the membrane seal allows the beveled front end of a needle to be pushed through the membrane and puncture the seal as it passes through and will not tear, but will stretch as the forward motion of the needle continues and conform to the profile of front portion of the needle base and allow it to engage the interior of the catheter base. The needle may be inserted into the catheter in the usual manner and the needle and catheter may be used just as any standard catheter-needle assembly. When the needle is withdrawn from the catheter, the membrane seal resumes its original position, except that it has a very tiny hole where the needle penetrated. Under normal use conditions, the resilient material of the membrane seal will close the hole to a diameter so small that no leakage occurs. Thus, the membrane seal prevents fluid from leaking from the catheter until such time as the connection is made at the base to complete the fluid injection or withdrawal procedure.